You know what I don't understand, if Marie didn't have jewels, then why didn't Emakov's bayonet piece her bodice when he attempted stab her with the bayonets after she and Anastasia awoke as their bodies where being taken out of the cellar?
I think it's obvious Baroness Buxhoevden did give the information to the guards the info about the hidden jewels based upon the evidence left in his memoirs.
But you can clearly read that they only found jewels on Olga, Tatiana, and Anastasia. Not Marie. According to FOTR (which includes source notes to back up all of their claims), Yurovsky thought it was because indeed, AF kind of shunned Maria in the end.
I could be Maria wasn't allowed to carry the jewels. Alexandra's reasoning was probably that "if we can't trust her with the guards then we can't trust her to hold the jewels."
Another reason could be that Maria didn't have any sown into her clothes because none of the jewels were sown in the GD's clothes until AFTER Maria was in Ekaterinburg with her parents and Alexandra wrote to the girls to "dispose of the medicines.